This invention is in the field of pulleys and sheaves of the type frequently employed for supporting and moving cable stretches employed in conveying cans and the like. More specifically, the present invention is directed to a new method of reconditioning worn metal sheave, which were previously scrapped, to provide a resultant new and improved sheave construction superior to the original and which can be reconditioned many times at substantially less cost than the cost of a new sheave.
Metal pulleys and sheaves employed in cable conveyors in canneries and the like are subjected to a great deal of rough usage and corrosive chemicals and consequently rapidly become worn with frequent replacement being necessary. Usually, one of the rims of the sheaves is subjected to greater friction than the other and it consequently wears downwardly to a substantially greater degree than the other rim to the point at which the rim becomes ineffective for retaining the conveyor cable in position in the sheave and consequently has to be replaced. Another substantial problem with both new and worn metal sheaves employed for conveying cans on cable conveyors such as in canneries, bottlers and the like is the fact that engagement of the can bottoms with the metal sheaves creates a great amount of objectionable clatter and noise which is environmentally objectionable.
Additionally, the cans on cable conveyors are sometimes stopped for substantial time periods while the conveyor continues to operate; under such conditions, metal sheaves will soon wear or damage can bottoms against which they continue to rotate.
Others have attempted to cast polyurethane on metal supports to provide a trunnion; however, geometric imbalance of such devices has resulted in a high failure rate of such devices.
Therefore, it is the primary object of this invention to provide a new and improved method of reconditioning metal sheaves to permit subsequent usage and reconditioning substantially indefinitely.
Yet another object of the present invention is the provision of a new and improved sheave construction that is substantially quieter in operation than prior known cable conveyor sheaves.
The foregoing and other objects of this invention are achieved by the present invention through the reconditioning of worn metal sheaves by first turning the sheaves to completely remove the most heavily worn flange along with the original groove and a substantial portion of the other less worn flange. Basically, the sheave is turned to provide three cylindrical outer surfaces in side-by-side relationship with the center cylindrical surface being connected to the outer surfaces by radial surfaces. All of the turned cylindrical and radial surfaces are provided with a roughened texture and the metal core body formed as a result of the turning operation is then positioned in a circular mold and uncured polyurethane components are poured into the mold to provide an encircling plastic rim body adhering to the roughened surface of the metal core body. The plastic rim body is then itself turned about the geometric center of the metal core body to provide first and second flanges between which a groove is positioned and which is dimensioned for receiving the cable of the cable conveyor system with which the sheave is to be employed. One side face of the resultant sheave is formed of plastic. The sheave is installed in the conveyor with the plastic side facing upwardly so that cans conveyed by the conveyor ride across the plastic side so that there is no metal to metal contact and the resultant noise is substantially less than is the case with metal sheaves having metal components engaged by the cans. Moreover, when the polyurethane rim components become worn, they can be stripped from the metal body and replaced by repeating the molding and turning procedures at substantially less cost than the cost of a new metal sheave.
A better understanding of the preferred inventive embodiments of the method and the inventive item will be achieved when the following detailed description is considered in conjunction with the appended drawings in which like reference numerals are used for the same parts in different figures.